Heat exchanger

ABSTRACT

A heat exchanger that achieves a reduction in the dimensions of the header pipes, a sufficient level of strength against pressure and a structure that allows the caps to be washed thoroughly during the washing process is provided At each of the caps closing off the two ends of the cylindrical portion constituting a header pipe, a circular groove at which the circumferential edge at an end of the cylindrical portion is fitted over the entire circumference is formed to completely fit the cylindrical portion inside the cap so that the dimensions of the header pipe along the axial direction are reduced. In addition, by forming a thick portion at a closing portion, the pressure withstanding capability of the cap is improved. The cap also has a projected portion at its outer flat surface.

TECHNICAL FIELD

The present invention relates to a heat exchanger provided with a headerpipe, the two ends of which are closed off with caps.

BACKGROUND ART

In a heat exchanger disclosed in Japanese Examined Utility ModelPublication No. H7-3173, one end of the header, and more specifically,the lower lid closing off the lower end of the header, is provided witha collar, a fitting portion projecting out at the upper surface of thecollar and a retaining projection projecting out at the lower surface ofthe collar, and the heat exchanger is mounted at a vehicle body byfitting the retaining projection at a retaining hole constituted of avibration-damping rubber provided at the lower mounting plate secured tothe vehicle body.

In addition, Japanese Unexamined Utility Model publication No. H5-45482discloses a structure achieved by forming a side projection as anintegrated part of a lid closing off the opening at the lower end of theheader pipe and providing an insertion pin at the lower surface of thisside projection so that the insertion pin is offset from the center ofthe axis of the header pipe along a specific direction. By adopting thisstructure, the position of the insertion pin can be selected freely overa wide range.

The invention disclosed in Japanese Unexamined Patent publication No.H5-332693 achieves simplification in bracket mounting by providing amale screw that is set erect at the outer end surface of a header capclosing off the lower end of the header pipe.

The invention disclosed in Japanese Unexamined Patent Publication No. H9-26282 is provided with a lid assuming a structure different from thatof the lid having the side projection disclosed in Japanese UnexaminedUtility Model Publication No. H6-45482 mentioned above. The liddisclosed in this publication has an inward projection and a sideprojection provided as an integrated part of the inward projection andprojecting out along the direction of the width of the tubes and isformed as a block body achieving a roughly L-shape in the plan view.

As an examination of the examples quoted above reveals, since the lowerend of a heat exchanger mounted at a vehicle body is set near thevehicle body side panel, a means for retention to retain the heatexchanger at the vehicle body panel is provided at the lid that closesoff the lower end of the tubes of the heat exchanger. However, it is notdesirable to provide a means for retention such as a pin as anintegrated part of the lid, since the pin tends to become skewed duringthe brazing process to such an extent that, in extreme cases, it can nolonger be fitted at the mounting hole at the vehicle.

In addition, reflecting the increasing need for a reduction in theengine room space in recent years, the space available for mounting theheat exchanger has become smaller, thereby necessitating reduceddimensions in the heat exchanger.

Thus, the heat exchanger itself must become more compact. The lid (cap),which is normally manufactured through cold forging or the like, must bewashed after it is formed since impurities such as the mold releasingagent and the press oil adhere to the manufactured cap. If the end ofthe cap is formed in a flat shape in this situation, a problem ariseswhile washing the cap in that it may not be washed thoroughly. Inaddition, if the lid is formed in a flat shape, it is necessary toassure a specific thickness for the lid so that it can withstandpressure applied to the lid.

Accordingly, an object of the present invention is to provide a heatexchanger achieving a reduction in the header pipe dimensions and havinga cap with a sufficient degree of strength against pressure, which canbe washed thoroughly when washing the lid.

SUMMARY OF THE INVENTION

In order to achieve the object described above, in the heat exchangeraccording to the present invention comprising, at least, a pair ofheader pipes having inflow/outflow pipes through which a heat exchangingfluid flows in and out, a plurality of tubes communicating between thepair of header pipes and fins provided between the individual tubes, theheader pipes are each provided with a cylindrical portion havinginsertion holes, into which the tubes are inserted and a pair of capsthat close off the openings at the two ends of the cylindrical portion.The caps are each provided with a closing portion that closes off theopen ends, a circumferential wall portion formed at the circumferentialedge of the closing portion to be externally fitted at thecircumferential edge at the end of the cylindrical portion and acircular groove formed between the closing portion and the base end atthe inner circumferential surface of the circumferential wall portion atwhich the end of the cylindrical portion is fitted over the entirecircumference, and the closing portion has a thick portion locatedinside the circular groove.

Thus, by adopting the present invention having the circular groove, inwhich the circumferential edge at the end of the cylindrical portion isfitted over the entire circumference, formed at each cap closing off oneof the two ends of the cylindrical portion constituting each of theheader pipes, the cylindrical portion is fitted inside the cap to reducethe dimensions of the header pipe along the axial direction. Inaddition, since the thick portion is formed at the closing portion, thethickness of the closing portion can be maintained at a specific valueto achieve the object described above.

Furthermore, the side surface of the thick portion located toward thecylindrical portion is formed in an indented shape. This makes itpossible to form the inner side surface of the thick portion in an archto improve the strength against internal pressure.

The cap is provided with a projected portion projecting out along thedirection of the length of the cylindrical portion at the outer endsurface located on the opposite side from the cylindrical portion. Onesuch projected portion may be formed at an approximate center of theouter end surface or a plurality of such projected portions may beformed over consistent intervals near the circumferential edge of theouter end surface.

Since the presence of the projected portions at the flat outer endsurface of the cap prevents the cap from becoming placed in surfacecontact during the washing process, the washing solution is allowed toreach the end surface of the cap with a high degree of reliability toassure thorough washing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial frontal view illustrating the structure of a heatexchanger in an embodiment of the present invention;

FIG. 2 is a sectional view in an enlargement of a header tank end in anembodiment of the present invention;

FIG. 3 illustrates a cap employed in a first embodiment of the presentinvention, with

FIG. 3(a) presenting a plan view of the cap,

FIG. 3(b) presenting its side elevation and

FIG. 3(c) presenting a sectional view along line of FIG. 3(a);

FIG. 4 is a sectional view in an enlargement of a header tank end,illustrating a cap adopted in a second embodiment,

FIG. 5 illustrates a cap adopted in a third embodiment of the presentinvention, with

FIG. 5(a) presenting an enlarged frontal view of the cap around a headertank end and

FIG. 5(b) presenting its plan view;

FIG. 6 illustrates a cap adopted a fourth embodiment of the presentinvention, with

FIG. 6(a) presenting an enlarged frontal view of the cap around a headertank end and

FIG. 6(b) presenting its plan view; and

FIG. 7 illustrates a cap adopted in a fifth embodiment of the presentinvention, with

FIG. 7(a) presenting an enlarged frontal view of the cap around a headertank end and

FIG. 7(b) presenting its plan view.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is now explained in further detail in reference tothe attached drawings.

A heat exchanger 1 shown in FIG. 1 may be, for instance, a condenserconstituting a portion of a freezing cycle in an air-conditioning systemfor vehicles mounted in a vehicle. The condenser 1 comprises a pair ofheader pipes 2, a plurality of tubes 3 communicating between the pair ofheader pipes 2, fins 4 alternately laminated with the plurality of tubes3 and a pair of side plates 5 holding the tubes 3 and the fins 4 at thetwo ends along the laminating direction, and is installed within avehicle panel 6 provided in the engine room together with the radiator(not shown).

In this embodiment, the header pipes 2 include an intake-side headerpipe 2 a located on one side and provided with a coolant intake pipe 7and an outlet side header pipe 2 b located on the other side andprovided with a coolant outlet pipe 8. In addition, the intake-sideheader pipe 2 a is divided into two internal spaces 21 and 22 by apartitioning plate 9 a, whereas the outlet-side header pipe 2 b isdivided into two internal spaces 23 and 24 by a partitioning plate 9 b.It is to be noted that the header pipes 2 are each constituted of acylindrical portion 20 having formed therein a plurality of tubeinsertion holes 20 a at which the tubes 3 are inserted and caps 30 eachclosing off an opening at one of the two ends of the cylindrical portion20.

In this structure, a coolant flowing into the internal space 21 throughthe coolant intake pipe 7 travels through the tubes 3 communicating withthe internal space 21 to flow into the internal space 23. The coolant,having flowed into the internal space 23 travels through the tubes 3communicating between the internal space 23 and the internal space 22 toreach the internal space 22, further travels through the tubes 3communicating with the internal space 22 to flow into the internal space24, and is finally discharged through the coolant outlet pipe 8 via theinternal space 24. Thus, the coolant becomes condensed by dischargingheat to the air passing through the fins 4 via the fins 4 while ittravels through the three passes. As a result, a high-pressure gascoolant and a high-pressure liquid coolant condensed from thehigh-pressure gas coolant are both present in the condenser 1.

As illustrated in FIGS. 3(a), 3(b) and 3(c), the caps 30 at the headerpipes 2 are each constituted of a closing portion 31 that closes off anopen end 25 of the cylindrical portion 20, a circumferential wallportion 32 formed at the circumferential edge of the closing portion 31to be externally fitted at the circumferential edge of the end 25 of thecylindrical portion 20 and a circular groove 33 formed between theclosing portion 31 and the base end of the inner circumferential surfaceof the circumferential wall portion 32 at which the end 25 of thecylindrical portion 20 is inserted over the entire circumference. Inaddition, a thick portion 34 is formed at the closing portion 31 in anarea located within the circular groove 33. At a front end edge 36 ofthe circumferential wall portion 32, pipe insertion guide pieces 37project out at specific positions.

Thus, as shown in FIG. 2, the end 25 of the cylindrical portion 20 isinserted and secured at the circular groove 33 formed at the cap 30 toallow the dimensions of the header pipe 2 along the longitudinaldirection to be set smaller by a specific degree. In addition, since thebrazing material clad at the cylindrical portion 20 and/or the innercircumferential surface of the circumferential wall portion 32 of thecap 30 flows into, and is collected at the circular groove 33 to fix thecylindrical portion 20 and the cap 30 together during the furnacebrazing process, the cylindrical portion 20 and the cap 30 can be brazedwith reliability.

Furthermore, while the cylindrical portion 20, whose circumferentialedge is round, withstands the internal pressure within the header pipe 2with a high degree of reliability, the internal pressure is directlyapplied to the flat cap 30. Accordingly, the thick portion 34 is formedat the closing portion 31 of the cap 30 in the area located inside thecircular groove 33 to achieve a specific level of pressure withstandingcapability against the internal pressure within the header pipe 2.

The second embodiment illustrated in FIG. 4 adopts a structure having anindented portion 38 formed in an arch at the thick portion 34 in thearea constituting the inner surface of the header pipe 2 to furtherimprove the pressure withstanding capability of the thick portion 34. Itis to be noted that in the second embodiment and the subsequentembodiments described below, the same reference numbers are assigned toidentical components or components achieving similar functions to thosein the first embodiment to preclude the necessity for repeatedexplanation thereof.

In addition, since the mold releasing agent, the press oil and the likeadhere to the cap 30 manufactured through cold forging or the like, itis necessary to wash off these substances. Washing the caps is a crucialprocess that must be implemented without fail when manufacturing thecaps 30. In order to ensure that the cleaning solution comes intocontact with the flat surface of each cap reliably, a projected portion40 projecting out at an approximate center of the outer flat surface 30a of the cap 30 is provided in the third embodiment shown in FIGS. 5(a)and 5(b). Since the projected portions 40 prevent the outer flatsurfaces 30 a from becoming stuck together during the washing process,thorough washing can be achieved with a high degree of reliability.

In the fourth embodiment illustrated in FIGS. 6(a) and 6(b), a pluralityof projected portions 41 are provided over specific intervals near theexternal circumferential edge of the outer flat surface 30 a of each cap30. Thus, since the outer flat surfaces 30 a can be effectivelyprevented from becoming stuck together, thorough washing is achievedwith a high degree of reliability. It is to be noted that while threeprojected portions 41 are provided in this embodiment, no specificrestrictions are imposed with regard to the number of projected portionsas long as three or more projected portions are provided.

Furthermore, in the fifth embodiment illustrated in FIGS. 7(a) and 7(b),a plurality of projections 42 are provided over specific intervals nearthe external circumferential edge of the outer flat surface 30 a of eachcap 30. Thus, since the outer flat surfaces 30 a can be effectivelyprevented from becoming stuck together, thorough washing is performed ina reliable manner. In this case, three or more projections 42 may beprovided without any particular restrictions, as in the case of theprojected portions 41 described above.

Industrial Applicability

As explained above, according to the present invention in which each capclosing off one of the two ends of the cylindrical portion constitutingeach header pipe of the heat exchanger is provided with a circulargroove at which the front end of the cylindrical portion is fitted, thedimensions of the header pipe can be reduced to a degree correspondingto the length of the front end of the cylindrical portion that is placedwithin the circular groove to achieve a reduction in the amount of spacerequired within the engine room. In addition, with the thick portionformed at the closing portion that closes off each of the two ends ofthe cylindrical portion, the pressure withstanding capability againstthe internal pressure at the header pipe is improved, and at the sametime, with the brazing material flowing into the groove, the cylindricalportion and the cap can be brazed together more reliably to improve thedurability of the heat exchanger.

Furthermore, by forming at least one projected portion or projection atthe outer flat surface of the cap, the manufactured cap is alwaysthoroughly washed during the washing process to make it possible todispense with a screening process or an inspection process that wouldotherwise have to be implemented after the washing process. As a result,a reduction in the cap manufacturing cost is achieved.

What is claimed is:
 1. A heat exchanger comprising at least a pair ofheader pipes each having an inflow pipe or an outflow pipe through whicha heat exchanging fluid flows in or out, a plurality of tubescommunicating between said pair of header pipes and fins providedbetween said tubes, characterized in that: said header pipes are eachprovided with a cylindrical portion having insertion holes through whichsaid tubes are inserted and a pair of caps each blocking off one of theopenings at the two ends of said cylindrical portion, said caps are eachconstituted of a closing portion that closes off said open end, acircumferential wall portion formed at the circumferential edge of saidclosing portion to be externally fitted with the circumferential edge atan end of said cylindrical portion and a circular groove formed betweensaid closing portion and the base end of the inner circumferentialsurface of said circumferential wall portion at which said end of saidcylindrical portion is inserted over the entire circumference, and saidclosing portion has a thick portion within said circular groove.
 2. Aheat exchanger according to claim 1, characterized in that: a sidesurface of said thick portion located toward said cylindrical portion isformed in an indented shape.
 3. A heat exchanger according to claim 1,characterized in that: said caps are each provided with at least oneprojected portion projecting out along the direction of the length ofsaid cylindrical portion at an outer end surface on the side oppositefrom said cylindrical portion.
 4. A heat exchanger according to claim 3,characterized in that: said at least one projected portion comprises aprojected portion formed at an approximate center at said outer endsurface.
 5. A heat exchanger according to claim 3, characterized inthat: said at least one projected portion comprises a plurality ofprojected portions formed over consistent intervals near thecircumferential edge of said outer end surface.
 6. A heat exchangeraccording to claim 2, characterized in that: said caps are each providedwith a projected portion projecting out along the direction of thelength of said cylindrical portion at an outer end surface on the sideopposite from said cylindrical portion.